Explosive molding powder slurry processing in a nonaqueous medium using a mixed solvent lacquer system

ABSTRACT

A method of processing an explosive molding powder. The method comprises providing a nonaqueous slurry comprising at least one nitrate compound, an inert fluorocarbon medium, and, optionally, a water-reactive additive. The at least one nitrate compound comprises at least one nitramine, at least one nitrate ester, at least one nitrated aromatic, or mixtures thereof. A lacquer system comprising at least two organic solvents, at least one binder, and, optionally, at least one plasticizer is also provided. The organic solvents in the lacquer system may comprise at least one binder-soluble organic solvent and at least one binder-insoluble organic solvent. The nonaqueous slurry and the lacquer system are combined to form granules of the explosive molding powder. A lacquer system and solutions used in processing the explosive molding powder are also disclosed.

GOVERNMENT LICENSE RIGHTS

The U.S. Government has a paid-up license in this invention and theright in limited circumstances to require the patent owner to licenseothers on reasonable terms as provided for by the terms of Contract No.DAAE30-00-9-0806.

FIELD OF THE INVENTION

The present invention relates to processing of an explosive moldingpowder. More specifically, the present invention relates to processingthe explosive molding powder using a lacquer system and a nonaqueousslurry.

BACKGROUND OF THE INVENTION

Explosive molding powders are known in the art and are used in varioustypes of ordnance, such as grenades, land mines, missile warheads, anddemolition explosives. The explosive molding powder is extrudable orpressable into a desired shape for use in the ordnance. Typically, theexplosive molding powder is formed by adding a filler, such as anitramine, to water to form an aqueous slurry. The aqueous slurry isstirred to suspend the filler in the water. A binder is then dissolvedin an organic solvent to form a lacquer, which is added to the aqueousslurry. As the lacquer contacts the filler, particles of the filleragglomerate and a coating of the binder forms on the filler. The organicsolvent is subsequently removed using heat and an air purge to enhancecoating of the filler by the binder. The explosive molding powder isthen filtered from the aqueous slurry and dried to produce hardgranules.

One problem with producing explosive molding powders by this process isthat nitramine-based molding powders are prone to agglomeration, orcrashing. While some agglomeration of the filler is necessary to formthe granules, too much agglomeration causes the nitramine-based moldingpowders to stick to surfaces of processing equipment, which results inlow yields and reduced molding powder quality of the nitramine-basedmolding powders. Therefore, to form granules of a desired size, theagglomeration of the filler must be controlled.

Recently, there has been interest in forming aluminized, explosivemolding powders, which incorporate aluminum particles into the explosivemolding powders. Since aluminum particles smaller than 2 μm aregenerally water-reactive, nonaqueous media, rather than aqueousslurries, have been investigated to process the aluminized, explosivemolding powder. For instance, fluorocarbon media have been used toprocess explosive molding powders, as disclosed in U.S. Pat. No.5,750,921 to Chan et al. To form the explosive molding powder, a highexplosive is suspended in the fluorocarbon medium. A lacquer of ethylacetate and a binder is then added to the suspended high explosive toform the molding powder, which is filtered, dried, and pressed intoexplosive pellets. In this process, the single solvent lacquer does notprovide a mix cycle that allows easy isolation of the explosive moldingpowder. Therefore, the yield and, potentially, the quality of theexplosive molding powder are reduced.

It would be desirable to provide a repeatable method of processing anexplosive molding powder from a nonaqueous slurry to produce a highyield of a quality explosive molding powder.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a method of processing an explosivemolding powder. The method comprises providing a nonaqueous slurrycomprising at least one nitrate compound in an inert fluorocarbonmedium. As used herein, the term “nitrate compound” refers to at leastone nitramine, at least one nitrate ester, at least one nitratedaromatic, or mixtures thereof The nitrate compound may be selected fromthe group consisting of hexanitrohexaazaisowurtzitane (“CL-20”),cyclotetramethylene tetranitramine (“HMX”), pentaerythritol tetranitrate(“PETN”), hexanitrostilbene (“HNS”),2,4,6-trinitro-1,3,5-benzenetriamine (“TATB”),cyclo-1,3,5-trimethylene-2,4,6-trinitramine (“RDX”), and mixturesthereof in the inert fluorocarbon medium. The inert fluorocarbon mediummay be selected from the group consisting of perfluoroheptane (C₇F₁₆),perfluorooctane (C₈F₁₈), perfluorotributylamine, perfluorocyclic ether,and mixtures thereof. The nonaqueous slurry may optionally include awater-reactive additive, such as aluminum, boron, or magnesium.

A lacquer system comprising at least two organic solvents and at leastone binder is also provided. The at least two organic solvents of thelacquer system may include at least one binder-soluble organic solventand at least one binder-insoluble organic solvent. In one embodiment,the binder-soluble organic solvent may be ethyl acetate and thebinder-insoluble organic solvent may be ethanol. The at least one bindermay be selected from the group consisting of cellulose acetate butyrate(“CAB”), a fluoroelastomer, ethyl vinyl acetate, polyisobutylenepolymer, nylon, a thermoplastic polyester elastomer, and a polyetherblock amide. The lacquer system may optionally comprise a plasticizerselected from the group consisting of bis-dinitropropyl acetal andbis-dinitropropyl formal (“BDNPA/F”), isodecyl pelargonate (“IDP”),dioctyl adipate (“DOA”), dioctyl sebecate (“DOS”), a glycidyl azidepolymer (“GAP”), and mixtures thereof

The lacquer system and the nonaqueous slurry are combined to formgranules of the explosive molding powder. The granules may compriseparticles of the nitrate compound coated with the binder. At least onerinse solution may also be added to the combined lacquer system and thenonaqueous slurry to form the granules. The rinse solution may compriseat least one binder-soluble organic solvent and at least onebinder-insoluble organic solvent. The lacquer system, the inertfluorocarbon medium, and the rinse solution(s) may be removed to formthe granules.

The present invention also relates to a lacquer system for processing anexplosive molding powder. The lacquer system comprises at least twoorganic solvents and at least one binder. A first organic solvent of theat least two organic solvents is formulated to solubilize the binder anda second organic solvent is formulated so that the at least one binderis insoluble. The first organic solvent may be present fromapproximately 25% to approximately 75% of a total volume of the lacquersystem while the second organic solvent may be present fromapproximately 25% to approximately 75% of the total volume. In oneembodiment, the first organic solvent may be ethyl acetate and thesecond organic solvent may be ethanol. The binder may be selected fromthe group consisting of cellulose acetate butyrate, a fluoroelastomer,ethyl vinyl acetate, polyisobutylene polymer, nylon, a thermoplasticpolyester elastomer, and a polyether block amide.

The present invention also relates to solutions used in processing anexplosive molding powder. The solutions comprise a lacquer systemcomprising at least two organic solvents and at least one binder and anonaqueous slurry comprising at least one nitrate compound in an inertfluorocarbon medium. The at least one binder may be soluble in a firstorganic solvent of the at least two organic solvents and may beinsoluble in a second organic solvent of the at least two organicsolvents. The first organic solvent may be present from approximately25% to approximately 75% of a total volume ofthe lacquer system whilethe second organic solvent may be present from approximately 25% toapproximately 75% of the total volume. In one embodiment, the firstorganic solvent may be ethyl acetate and the second organic solvent maybe ethanol. The at least one binder may be selected from the groupconsisting of cellulose acetate butyrate, a fluoroelastomer, ethyl vinylacetate, polyisobutylene polymer, nylon, a thermoplastic polyesterelastomer, and a polyether block amide. The lacquer system may alsocomprise at least one plasticizer selected from the group consisting ofBDNPA/F, IDP, DOA, DOS, GAP, and mixtures thereof.

The nitrate compound in the nonaqueous slurry may be at least onenitramine, at least one nitrate ester, at least one nitrated aromatic,or mixtures thereof and may be selected from the group consisting ofCL-20, HMX, PETN, HNS, TATB, RDX, and mixtures thereof The inertfluorocarbon medium may be selected from the group consisting ofperfluoroheptane (C₇F₁₆), perfluorooctane (C₈F₁₈),perfluorotributylamine, perfluorocyclic ether, and mixtures thereof. Thenonaqueous slurry may also comprise a water-reactive additive, such asaluminum, magnesium, or boron.

DETAILED DESCRIPTION OF THE INVENTION

A lacquer system is disclosed for processing an explosive moldingpowder. As used herein, the term “lacquer system” refers to a mixedsolvent lacquer system that includes at least two organic solvents andat least one binder, which is dissolved in at least one of the organicsolvents. The lacquer system is added to a nonaqueous slurry thatincludes at least one nitrate compound in a nonaqueous medium. As usedherein, the term “nitrate compound” refers to at least one nitramine, atleast one nitrate ester, at least one nitrated aromatic, or mixturesthereof. Optionally, the nonaqueous medium may include at least onewater-reactive additive. Since the lacquer system and the nonaqueousslurry do not include water, the lacquer system may be used to processexplosive molding powders having water-reactive additives. The lacquersystem may produce a high yield of the explosive molding powder, whichhas good safety properties and a low void content. Effective andrepeatable processing of the explosive molding powder is based on thesolubility of the binder(s) in the lacquer system.

The nonaqueous slurry may be formed by suspending the nitrate compoundin the nonaqueous medium. The nitrate compound may include, but is notlimited to, CL-20, HMX, PETN, HNS, TATB, RDX, or mixtures thereof. Thenitrate compound may have a low solubility in the nonaqueous medium toprovide effective processing. The nitrate compound used in thenonaqueous medium may have a particle size ranging from a submicronparticle size (less than approximately 1 μm) to a particle size ofseveral hundred μm. For instance, the nitrate compound may have a fineparticle size of approximately 2 μm, or a coarse particle size, such asa particle size ranging from approximately 100 μm to approximately 400μm. In one embodiment, the nitrate compound is CL-20 having a 2 μmparticle size, or HMX. The nitrate compound may be present in thenonaqueous medium in an amount sufficient to produce a desired amount ofthe nitrate compound in the explosive molding powder. For instance, thenitrate compound may be present in the nonaqueous medium fromapproximately 10% to approximately 30%.

The water-reactive additive, if present, may also be suspended in thenonaqueous medium. The water-reactive additive may include, but is notlimited to, a water-reactive metal, such as aluminum, magnesium, boron,or mixtures thereof. The water-reactive additive used in the explosivemolding powder may have a small particle size, such as a particle sizeof less than approximately 2 μm. The water-reactive additive may bepresent in the nonaqueous slurry in an amount sufficient to produce anexplosive molding powder having from approximately 1 weight percent (“wt%”)to approximately 30 wt % of the water-reactive additive. In oneembodiment, the water-reactive additive is aluminum. The aluminum may befine aluminum, having a particle size from approximately 1 μm toapproximately 5 μm, or ultra-fine aluminum, having a particle size ofless than approximately 1 μm. In one embodiment, the aluminum is Alex®,an ultra-fine, nano-aluminum powder having an average particle size ofapproximately 210 nm. Alex® is available from Argonide Corp. (Sanford,Fla.).

The nonaqueous medium may be an inert fluorocarbon medium in which thenitrate compound has a low solubility. The inert fluorocarbon medium mayinclude, but is not limited to, a perfluoropolyether, perfluoroheptane(C₇F₁₆), perfluorooctane (C₈F₁₈), perfluorotributylamine,perfluorocyclic ether, or mixtures thereof. The inert fluorocarbonmedium may also have a low boiling point so that the inert fluorocarbonmedium is easily removed under drying conditions used in processing theexplosive molding powder. For instance, the inert fluorocarbon mediummay have a boiling point ranging from approximately 60° C. toapproximately 100° C. Inert fluorocarbon media are known in the art andare available from numerous sources, such as from 3M (Maplewood, Minn.).In one embodiment, the nonaqueous medium is Fluoroinert™ ElectronicLiquid FC-77, which is a thermally stable, fully fluorinated fluoroinertliquid that is available from 3M. Fluoroinert™ Electronic Liquid FC-77is nonflammable, relatively nontoxic, and is not regulated as a volatileorganic compound. Fluoroinert™ Electronic Liquid FC-77 includes 75%perfluorooctane and 25% perfluorocyclic ether, has a boiling point of97° C., a density of 1.78 g/cc, and a dielectric constant of 1.86.

Other inert fluorocarbon media having similar properties and a boilingpoint within the range of from approximately 60° C. to approximately100° C. are known in the art and may be used as the nonaqueous medium.Inert fluorocarbon media having higher boiling points may also be usedas the nonaqueous medium. However, more stringent drying conditions maybe necessary to remove the inert fluorocarbon medium if it has a higherboiling point. A sufficient amount of the inert fluorocarbon medium maybe present in the nonaqueous slurry so that when the lacquer system andthe nonaqueous slurry are combined, the lacquer system is diluted by theinert fluorocarbon medium, preventing particles of the nitrate compoundfrom growing quickly and agglomerating to surfaces of the processingequipment. However, the amount of the inert fluorocarbon medium shouldnot be so high as to impede the growth rate of the nitrate compoundparticles, which would result in the formation of small and highlysensitive granules of the explosive molding powder.

The lacquer system may include at least two organic solvents that aremiscible, or at least partially miscible, with each other. The lacquersystem may be immiscible, or at least partially immiscible, with theinert fluorocarbon medium. The effectiveness of the lacquer system toprocess the explosive molding powder may directly depend on solubilityof the binder in the lacquer system. The binder may be soluble in atleast one of the organic solvents of the lacquer system and insoluble inanother of the organic solvents. The organic solvent in which the binderis soluble is referred to herein as the “binder-soluble organicsolvent.” Examples of binder-soluble organic solvents include, but arenot limited to, esters, ketones, alcohols, alkanes, ethers, amides,nitrites, and aromatics, such as ethyl acetate, acetone, isopropylacetate, propyl acetate, methyl propyl ketone, and methyl ethyl ketone.The binder may be substantially soluble in the binder-soluble organicsolvent, such as being at least approximately 80% soluble. The organicsolvent in which the binder is insoluble is referred to herein as the“binder-insoluble organic solvent.” Examples of binder-insoluble organicsolvents include, but are not limited to, esters, ketones, alcohols,alkanes, ethers, amides, nitrites, and aromatics, such as ethanol,methanol, propanol, and butanol. The binder may be substantiallyinsoluble in the binder-soluble organic solvent, such as being at leastapproximately 80% insoluble.

The organic solvents of the lacquer system may be volatile so that theyare easily removed under conditions used to dry the explosive moldingpowder. The binder-insoluble organic solvent may be more volatile thanthe binder-soluble organic solvent. However, the binder-insolubleorganic solvent may be less volatile than the binder-soluble organicsolvent. While the Examples herein describe a lacquer system having twoorganic solvents, the lacquer system may include more than two organicsolvents, provided that the binder is soluble in at least one of theorganic solvents and is insoluble in at least one of the organicsolvents.

The binder-soluble organic solvent may be present in the lacquer systemin an amount sufficient to dissolve the binder. However, the amount ofthe binder-soluble organic solvent may not be so great as to cause thenitrate compound to agglomerate and stick to the surfaces of theprocessing equipment. The amount of the binder-soluble organic solventmay also be sufficient to allow the binder to uniformly coat the nitratecompound particles during formation of the granules. Thebinder-insoluble organic solvent may be present in an amount sufficientto soften the granules on their outer surfaces and make the granulesmoldable. However, the binder-insoluble organic solvent may not softenthe granules to such an extent that the granules agglomerate and stickto the surfaces of the processing equipment. The binder-insolubleorganic solvent may also produce a smooth surface on the granules.Relative amounts of the binder-soluble organic solvent and thebinder-insoluble organic solvent that are used in the lacquer systemdepend on the nature of the binder that is used. For sake of exampleonly, the binder-soluble organic solvent may be present fromapproximately 25% to approximately 75% of a total volume of the lacquersystem, while the binder-insoluble organic solvent may be present fromapproximately 25% to approximately 75% of the total volume. In oneembodiment, the binder-soluble organic solvent and the binder-insolubleorganic solvent are each present at approximately 50% of the totalvolume of the lacquer system.

The binder may be CAB; a fluoroelastomer, such as Viton® (available fromDupont Dow Elastomers, LLC) or FLUOREL® from 3M; Estane®(C_(5.14)H_(7.5)N_(0.187)O_(1.76)) (available from Noveon, Inc.(Cleveland, Ohio)); ethyl vinyl acetate; polyisobutylene polymer; nylon;a thermoplastic polyester elastomer, such as HyTrel® 8184 (availablefrom E.I du Pont de Nemours and Company); or a polyether block amide,such as PEBAX® (available from Atofina Chemicals Inc.). The binder maybe present in the lacquer system in an amount that is sufficient to bindtogether particles of the nitrate compound in the explosive moldingpowder. For instance, the binder may be present from approximately 1 wt% to approximately 50 wt %.

Additional components may be present in the lacquer system or in thenonaqueous slurry, such as plasticizers, surfactants, antioxidants, orbees' wax, depending on the desired properties of the explosive moldingpowder. The plasticizer may be BDNPA/F, IDP, DOA, DOS, GAP; or mixturesthereof. If the plasticizer is BDNPA/F, the bis-dinitropropyl acetal andthe bis-dinitropropyl formal may be present in a weight ratio of thebis-dinitropropyl acetal to the bis-dinitropropyl formal ranging fromapproximately 45:55 to approximately 55:45. The surfactant may include,but is not limited to, a low molecular weight alcohol, such as 1-butanolor isopropanol. The antioxidant may include, but is not limited to,diphenylamine, an n-alkylnitroaniline, such as n-methylnitroaniline orn-ethylnitroaniline, or mixtures thereof.

In one embodiment, CAB is used as the binder, the binder-soluble organicsolvent is ethyl acetate, ethanol is used as the binder-insolubleorganic solvent, and the inert fluorocarbon medium is Fluoroinert™Electronic Liquid FC-77.

To process the explosive molding powder, the nitrate compound, the inertfluorocarbon medium, and, optionally, the water-reactive additive may becombined to form the nonaqueous slurry. To avoid electrostatic discharge(“ESD”)hazards, the water-reactive additive may be wetted with the inertfluorocarbon medium before it is mixed with the nitrate compound. Thenitrate compound, the water-reactive additive, and the inertfluorocarbon medium may be combined in a first reaction vessel withstirring and heating to keep the nitrate compound suspended. Duringprocessing of the explosive molding powder, the first reaction vesselmay be continuously stirred at a speed ranging from approximately 200revolutions per minute (“RPM”)to approximately 800 RPM. The firstreaction vessel may be maintained at a temperature below the boilingpoints of the inert fluorocarbon medium, the binder-soluble organicsolvent, and the binder-insoluble organic solvent, such as fromapproximately 20° C. to approximately 60° C.

The binder-soluble organic solvent and the binder-insoluble organicsolvent may be mixed with the binder in a second reaction vessel to formthe lacquer system. Additional components, such as one or more of theplasticizer, the surfactant, or the antioxidant may be added to thelacquer system. The lacquer system may then be added to the nonaqueousslurry with continuous stirring and heating. Upon addition of thelacquer system, particles of the nitrate compound may begin toagglomerate. The binder and any additional components may thenprecipitate on the nitrate compound particles, forming hard, roundgranules of the explosive molding powder. In other words, the binder andany additional components may form a coating on the nitrate compoundparticles. Desirably, a uniform coating of the binder and the additionalcomponents is applied to the nitrate compound particles. Uniform coatingof the nitrate compound particles may be determined by viewing thegranules by scanning electron microscopy.

The lacquer system may be added to the first reaction vessel at alacquer addition rate sufficient to produce the hard, round granules.Depending on the binder and the nitrate compound that are used, thelacquer addition rate may be adjusted to produce the granules of adesired size. The lacquer addition rate may also affect the void contentof the granules. Generally, a fast lacquer addition rate, such asaddition of the lacquer over a time period of approximately 1 minute toapproximately 5 minutes, grows the nitrate compound particles quicklyand produces granules having a low void content. In contrast, a slowlacquer addition rate, such as addition of the lacquer over a timeperiod of greater than approximately 10 minutes, grows small nitratecompound particles having a high void content. Desirably, the granuleshave a size from approximately 0.85 mm to approximately 4 mm. Thelacquer addition rate may be adjusted from approximately 1 minute toapproximately 15 minutes to produce the granules in this desired sizerange.

Small granules may be produced when the lacquer system is initiallyadded to the nonaqueous slurry. However, small granules are undesirablebecause they have reduced safety properties. Therefore, to increase thesize of the granules, at least one rinse solution may be added to thecombined nonaqueous slurry and the lacquer system. The rinse solutionmay include organic solvents that are selected based on the nitratecompound used in the nonaqueous slurry. The rinse solution may includethe same organic solvents as are used in the lacquer system. However,the relative amounts of each of the organic solvents in the rinsesolution may differ from the relative amounts in the lacquer solution.The binder-soluble organic solvent may be present in the rinse solutionfrom approximately 10% to approximately 90% of the total volume whilethe binder-insoluble organic solvent may be present from approximately10% to approximately 90% of the total volume. For sake of example only,if CL-20 is used as the nitrate compound, the rinse solution may include25% ethyl acetate and 75% ethanol. If HMX is used, the rinse solutionmay include 17% ethyl acetate and 83% ethanol. After the rinse solutionis added, the mixture of the nonaqueous slurry and the lacquer systemmay be stirred for approximately 10 minutes to approximately 50 minutesuntil the granules grow to the desired size.

The inert fluorocarbon medium and the organic solvents of the lacquersystem may be gradually removed from the first reaction vessel. Theorder in which the inert fluorocarbon medium and the organic solventsare removed may depend on the relative boiling points of the inertfluorocarbon medium and the organic solvents of the lacquer system.After removal, one or more of the inert fluorocarbon medium, thebinder-soluble organic solvent, or the binder-insoluble organic solventmay be collected for recycling or reuse. The inert fluorocarbon mediumand the lacquer system may be removed by one or more of heating thefirst reaction vessel, drawing a vacuum over the first reaction vessel,or flowing a gas over the first reaction vessel. For sake of exampleonly, the first reaction vessel may be heated to a temperature rangingfrom approximately 30° C. to approximately 60° C. The first reactionvessel may also be continuously stirred to assist in removing the inertfluorocarbon medium and the lacquer system. Since the binder-insolubleorganic solvent may be more volatile than the binder-soluble organicsolvent, the binder-insoluble organic solvent may be removed from thefirst reaction vessel before the binder-soluble organic solvent. Ifsurfactants or a rinse solution were used in the process, they may alsobe removed under these conditions.

After the inert fluorocarbon medium and the lacquer system are removed,the granules of the explosive molding powder may be filtered and dried.The granules may be dried by placing them in a vacuum oven forapproximately 12 hours to approximately 24 hours at a temperatureranging from approximately 120° F. (48° C.) to approximately 140° F.(60° C.). The resulting granules may be pressed or extruded intopellets, grains, or billets that are used in grenades, land mines,missile warheads, demolition explosives, or other ordnance.

The reaction vessels used to process the explosive molding powder may beconventional reaction vessels, such as slurry kettles or slurry mixers.The reaction vessel may be equipped with a stirrer, such as an impeller,and a heat source, such as a heating jacket, to provide stirring andheat during processing of the explosive molding powder.

In addition to producing the explosive molding powder from thenonaqueous slurry, the lacquer system may also be used to produce anexplosive molding powder from an aqueous slurry that includes at leastone nitrate compound. To process the explosive molding powder from theaqueous slurry, the binder-soluble organic solvent and thebinder-insoluble organic solvent may be insoluble in water. Since thelacquer system may be used with the aqueous slurry, it may also be usedto process explosive molding powders that do not include water-reactiveadditives, such as non-aluminized explosive molding powders oraluminized explosive molding powders having an aluminum particle size ofgreater than approximately 2 μm. The lacquer system may also be used toprocess explosive molding powders that have an increased solubility inthe inert fluorocarbon medium compared to their solubility in an aqueousmedium.

The explosive molding powder formed by the method of the presentinvention may include at least one binder and at least one nitratecompound. The nitrate compound may be present in the explosive moldingpowder from approximately 50 wt % to approximately 98 wt %. Desirably,the nitrate compound is present from approximately 70 wt % toapproximately 80 wt %. The binder may be present in the explosivemolding powder at less than approximately 10 wt %. The explosive moldingpowder may also include the one or more of the water-reactive additiveor the plasticizer.

The explosive molding powder processed by the method of the presentinvention has a high bulk density and improved impact propertiescompared to explosive molding powders processed by conventional methods.It is believed that the improvement in the bulk density and the impactproperties is the result of producing the explosive molding powder to besubstantially free of voids. For instance, the explosive molding powdermay have a void volume of less than approximately 3%.

The following includes an example of an aluminized explosive moldingpowder that was formed by the process of the present invention. Thisexample is merely illustrative and is not meant to limit the scope ofthe present invention in any way.

EXAMPLES

All three Examples used the same percentages of four ingredients (CL-20,aluminum, CAB, and BDNPA/F) to form 70 g mixes of the molding powder.The mixes produced in all three Examples were conducted in the sameone-liter mixer. The mixes described in Examples 1 & 2 used amicron-sized aluminum, while the mix in Example 3 used a nano-sizedaluminum.

Comparative Example 1 CL-20 Explosive Molding Powder IncludingMicron-sized Aluminum Prepared Using a Single Solvent Lacquer System

Mix RH-1803-31 (Comparative Example) of a CL-20 explosive molding powderwas processed using a lacquer having one organic solvent. To prepare theCL-20 explosive molding powder, 3.2% CAB was dissolved into 22 g ethylacetate to form the lacquer. 4.8% of the BDNPA/F was then added to thelacquer. To form the non-aqueous slurry, 77% CL-20 and 15% Valimet H-2aluminum were added to 400 g of FC-77 in a one-liter mixer. The ValimetH-2 aluminum was then wetted with FC-77 to avoid ESD hazards. The CL-20used in the formulation had a 3.5 μm particle size. The non-aqueousslurry was then stirred at 400 RPM to 600 RPM and heated to atemperature of 25° C.-30° C. The lacquer was then added to thenon-aqueous slurry over 5-15 minutes. An ethyl acetate rinse of 8 g wasadded slowly and the mixture was stirred for 15 minutes to 30 minutes toremove the ethyl acetate. During mixing, a small amount of moldingpowder adhered to the mixer, and the granules were small and had voids.Once the ethyl acetate was removed, the granules were filtered through a#4 Whatman filter and were dried overnight in a vacuum oven at atemperature of 120° F.-140° F.

The granules produced from mix RH-1803-31 had a high void content and ayield of 87%. The safety properties of mix RH-1803-31 are shown inTable 1. Impact properties of Mix RH-1803-31 were measured using animpact test developed by the Bureau of Explosives (“BOE”). Frictionproperties of Mix RH-1803-31 were measured using a friction testdeveloped by Allegheny Ballistics Laboratory (“ABL”). Electrostaticdischarge of Mix RH-1803-31 was measured using an ESD test developed byThiokol Corporation (“TC”). The BOE Impact Test, the ABL Friction Test,and the TC ESD Test are known in the art and, therefore, details ofthese tests are not included herein. Because of the high void content ofMix RH-1803-31, the BOE Impact was undesirably sensitive. TABLE 1 SafetyData for Mix RH-1803-31. Safety Data Mix RH-1803-31 BOE Impact (4 in.drop) 5 go, 5 no go ABL Friction 130 lb @ 8 ft/s TC ESD (J) >8

Example 2 CL-20 Explosive Molding Powder Including Micron-Sized AluminumPrepared Using a Two Solvent Lacquer System

Mix RH-1803-38 of a CL-20 explosive molding powder was processed using alacquer having two organic solvents. To prepare the CL-20 explosivemolding powder, 3.2% CAB was dissolved into a mixture of 50% (11 g)ethyl acetate and 50% (11 g) ethanol to form the lacquer system. 4.8% ofthe BDNPA/F was then added to the lacquer. To form the nonaqueousslurry, 77% CL-20 and 15% Valimet H-2 aluminum were added to 400 g ofFC-77 in a one-liter mixer. The Valimet H-2 aluminum was wetted withFC-77 to avoid ESD hazards. The CL-20 used in the formulation had a 3.5μm particle size. The non-aqueous slurry was then stirred at 370 RPM to500 RPM and heated to a temperature of 25° C.-30° C. The lacquer wasthen added to the non-aqueous slurry over 5-15 minutes. Two 4 g rinses,each composed of 75% ethanol & 25% ethyl acetate, were added slowly andthe mixture was stirred for 15 minutes to 30 minutes to remove the ethylacetate and ethanol. During stirring, mix RH-1803-38 did not adhere tothe mixer as did the granules in mix RH-1803-31. In addition, thegranules of mix RH-1803-38 were larger and did not have voids. Once theethyl acetate and ethanol were removed, the granules were filteredthrough a #4 Whatman filter and dried overnight in a vacuum oven at atemperature of 120° F.-140° F.

The granules produced from mix RH-1803-38 had a low void content and ayield of 99%. The safety properties of mix RH-1803-38 are shown in Table2. Because of the low void content of mix RH-1803-38, the BOE impact wassubstantially less sensitive than mix RH-1803-31. In addition, the yieldof mix RH-1803-38 was increased because there was not as much moldingpowder adhering to the mixer. TABLE 2 Safety Data for Mix RH-1803-38.Safety Data Mix RH-1803-38 BOE Impact (4 in. drop) 2 go, 8 no go ABLFriction 420 lb @ 8 ft/s TC ESD (J) >8

Example 3 CL-20 Explosive Molding Powder Including Nano-Sized AluminumProduced Using a Two Solvent Lacquer System

Mix JA-1878-20 of a CL-20 explosive molding powder was processed bydissolving 3.2% CAB into a mixture of 11 g (50%) ethyl acetate and II g(50%) ethanol to form the lacquer system. 4.8% BDNPA/F was added to thelacquer system. In a one-liter slurry mixer, 77% CL-20 and 15% Alex®were added to 400 g of FC-77 to form the nonaqueous slurry. The Alex®was wetted with FC-77 to avoid ESD hazards. The CL-20 used in theformulation had a 3.5 μm particle size. The nonaqueous slurry wasstirred at 250 RPM for 3 minutes. Then, the lacquer system was addedover 5.5 minutes and the stirring rate was increased to 370 RPM.

A vacuum was applied to the slurry mixer and the stirring rate wasincreased to 400 RPM. After 5 minutes of stirring, a rinse solution of 4g of 75% ethanol and 25% ethyl acetate was added to the slurry mixerover 3 minutes at 410 RPM. The stirring speed was then increased to 430RPM. After 2 minutes, an additional 4 g of 1:3 ethyl acetate/ethanol wasadded to the slurry mixer over 2 minutes and the stirring speedincreased to 440 RPM. After 1 minute, an additional 4 g of 75% ethanoland 25% ethyl acetate was added to the slurry mixer over 1.5 minutes.After 4 minutes, a 3 g rinse solution of 75% ethanol and 25% ethylacetate was added to the slurry mixer and the stirring speed increasedto 480 RPM. The mixture was stirred for 50 minutes at a stirring speedof 270 RPM to 470 RPM to remove the ethyl acetate and the ethanol. Then,the granules were filtered through a #4 Whatman filter and the granuleswere dried in a vacuum oven at 120° F.-130° F. overnight. The yield ofMix JA-1878-20 was 97.3%. Mix JA-1878-20 produced uniform granules ofthe CL-20 explosive molding powder and had no voids. The safetyproperties for Mix JA-1878-20 are shown in Table 3. TABLE 3 Safety Datafor Mix JA-1878-20. Safety Data Mix JA-1878-20 BOE Impact (4 in. drop) 1go, 9 no go ABL Friction (lb @ ft/s) 180 @ 8 TC ESD (J) >8

The mixes prepared using the mixed solvent lacquer system, as describedin Examples 2 and 3, exhibited improved impact properties and improvedyields compared to the mix prepared using one solvent in the lacquersystem, as described in Example 1.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been described in detailherein. However, it should be understood that the invention is notintended to be limited to the particular forms disclosed. Rather, theinvention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by thefollowing appended claims.

1. A method of processing an explosive molding powder, comprising:providing a nonaqueous slurry comprising at least one nitrate compoundin an inert fluorocarbon medium; providing a lacquer system comprisingat least two organic solvents and at least one binder; and combining thelacquer system and the nonaqueous slurry to form granules of theexplosive molding powder.
 2. The method of claim 1, wherein providing anonaqueous slurry comprising at least one nitrate compound in an inertfluorocarbon medium comprises providing at least one nitrate compoundselected from the group consisting of at least one nitramine, at leastone nitrate ester, at least one nitrated aromatic, and mixtures thereof.3. The method of claim 1, wherein providing a nonaqueous slurrycomprising at least one nitrate compound in an inert fluorocarbon mediumcomprises providing a nitrate compound selected from the groupconsisting of hexanitrohexaazaisowurtzitane (“CL-20”),cyclotetramethylene tetranitramine (“HMX”), pentaerythritol tetranitrate(“PETN”), hexanitrostilbene (“UNS”),2,4,6-trinitro-1,3,5-benzenetriamine (“TATB”),cyclo-1,3,5-trimethylene-2,4,6-trinitramine (“RDX”), and mixturesthereof in the inert fluorocarbon medium.
 4. The method of claim 1,wherein providing a nonaqueous slurry comprising at least one nitratecompound in an inert fluorocarbon medium comprises providing at leastone nitrate compound in an inert fluorocarbon medium selected from thegroup consisting of perfluoroheptane (C₇F₁₆), perfluorooctane (C₈F₁₈),perfluorotributylamine, perfluorocyclic ether, and mixtures thereof. 5.The method of claim 1, wherein providing a nonaqueous slurry comprisingat least one nitrate compound in an inert fluorocarbon medium comprisesproviding at least one nitrate compound in 75% perfluorooctane and 25%perfluorocyclic ether.
 6. The method of claim 1, wherein providing anonaqueous slurry comprising at least one nitrate compound in an inertfluorocarbon medium comprises providing an inert fluorocarbon mediumhaving a boiling point ranging from approximately 60° C. toapproximately 100° C.
 7. The method of claim 1, wherein providing anonaqueous slurry comprising at least one nitrate compound in an inertfluorocarbon medium comprises suspending the at least one nitratecompound in the inert fluorocarbon medium.
 8. The method of claim 1,wherein providing a lacquer system comprising at least two organicsolvents and at least one binder comprises providing a lacquer systemcomprising at least one binder-soluble organic solvent and at least onebinder-insoluble organic solvent.
 9. The method of claim 8, whereinproviding a lacquer system comprising at least one binder-solubleorganic solvent and at least one binder-insoluble organic solventcomprises providing from approximately 25% to approximately 75% of theat least one binder-soluble organic solvent and from approximately 25%to approximately 75% of the at least one binder-insoluble organicsolvent.
 10. The method of claim 1, wherein providing a lacquer systemcomprising at least two organic solvents and at least one bindercomprises providing a lacquer system that is immiscible in the inertfluorocarbon medium.
 11. The method of claim 1, wherein providing alacquer system comprising at least two organic solvents and at least onebinder comprises using ethyl acetate as at least one binder-solubleorganic solvent and ethanol as at least one binder-insoluble organicsolvent.
 12. The method of claim 1, wherein providing a lacquer systemcomprising at least two organic solvents and at least one bindercomprises providing at least one binder selected from the groupconsisting of cellulose acetate butyrate, a fluoroelastomer, ethyl vinylacetate, polyisobutylene polymer, nylon, a thermoplastic polyesterelastomer, and a polyether block amide.
 13. The method of claim 1,wherein combining the lacquer system and the nonaqueous slurry to formgranules of the explosive molding powder comprises agglomeratingparticles of the at least one nitrate compound.
 14. The method of claim1, wherein combining the lacquer system and the nonaqueous slurry toform granules of the explosive molding powder comprises coatingparticles of the at least one nitrate compound with the at least onebinder.
 15. The method of claim 1, further comprising providing awater-reactive additive in the nonaqueous slurry.
 16. The method ofclaim 15, wherein providing a water-reactive additive in the nonaqueousslurry comprises adding aluminum, magnesium, or boron to the nonaqueousslurry.
 17. The method of claim 1, further comprising providing at leastone plasticizer to the lacquer system.
 18. The method of claim 17,wherein providing at least one plasticizer to the lacquer systemcomprises adding at least one plasticizer selected from the groupconsisting of bis-dinitropropyl acetal and bis-dinitropropyl formal(“BDNPA/F”), isodecyl pelargonate (“IDP”), dioctyl adipate (“DOA”),dioctyl sebecate (“DOS”), a glycidyl azide polymer (“GAP”), and mixturesthereof.
 19. The method of claim 1, further comprising adding at leastone rinse solution to a combined lacquer system and the nonaqueousslurry.
 20. The method of claim 19, wherein adding at least one rinsesolution to the combined lacquer system and the nonaqueous slurrycomprises adding a rinse solution comprising the at least onebinder-soluble organic solvent and the at least one binder-insolubleorganic solvent.
 21. The method of claim 1, further comprising removingthe at least two organic solvents and the inert fluorocarbon medium toform the granules of the explosive molding powder.
 22. A lacquer systemfor processing an explosive molding powder, comprising: at least twoorganic solvents and at least one binder, wherein a first organicsolvent of the at least two organic solvents is formulated to solubilizethe at least one binder and a second organic solvent of the at least twoorganic solvents is formulated so that the at least one binder isinsoluble therein.
 23. The lacquer system of claim 22, wherein the firstorganic solvent is present from approximately 25% to approximately 75%of a total volume of the lacquer system and the second organic solventis present from approximately 25% to approximately 75% of the totalvolume of the lacquer system.
 24. The lacquer system of claim 22,wherein the first organic solvent is ethyl acetate and the secondorganic solvent is ethanol.
 25. The lacquer system of claim 22, whereinthe first organic solvent is present at approximately 50% of a totalvolume of the lacquer system and the second organic solvent is presentat approximately 50% of the total volume of the lacquer system.
 26. Thelacquer system of claim 22, wherein the least one binder is selectedfrom the group consisting of cellulose acetate butyrate, afluoroelastomer, ethyl vinyl acetate, polyisobutylene polymer, nylon, athermoplastic polyester elastomer, and a polyether block amide. 27.Solutions for processing an explosive molding powder, comprising: alacquer system comprising at least two organic solvents and at least onebinder; and a nonaqueous slurry comprising at least one nitrate compoundin an inert fluorocarbon medium.
 28. The solutions of claim 27, whereinthe at least one binder is soluble in a first organic solvent of the atleast two organic solvents and is insoluble in a second organic solventof the at least two organic solvents.
 29. The solutions of claim 28,wherein the first organic solvent is ethyl acetate and the secondorganic solvent is ethanol.
 30. The solutions of claim 28, wherein thelacquer system comprises from approximately 25% to approximately 75% ofthe first organic solvent and from approximately 25% to approximately75% of the second organic solvent.
 31. The solutions of claim 27,wherein the lacquer system is irniscible in the inert fluorocarbonmedium.
 32. The solutions of claim 27, wherein the at least one binderis selected from the group consisting of cellulose acetate butyrate, afluoroelastomer, ethyl vinyl acetate, polyisobutylene polymer, nylon, athermoplastic polyester elastomer, and a polyether block amide.
 33. Thesolutions of claim 27, wherein the at least one nitrate compound isselected from the group consisting of at least one nitramine, at leastone nitrate ester, at least one nitrated aromatic, and mixtures thereof.34. The solutions of claim 27, wherein the at least one nitrate compoundis selected from the group consisting of hexanitrohexaazaisowurtzitane(“CL-20”), cyclotetramethylene tetranitramine (“HMX”), pentaerythritoltetranitrate (“PETN”), hexanitrostilbene (“HNS”),2,4,6-trinitro-1,3,5-benzenetriamine (“TATB”),cyclo-1,3,5-trimethylene-2,4,6-trinitramine (“RDX”), and mixturesthereof in the inert fluorocarbon medium.
 35. The solutions of claim 27,wherein the inert fluorocarbon medium is selected from the groupconsisting of perfluoroheptane (C₇F₁₆), perfluorooctane (C₈F₁₈),perfluorotributylamine, perfluorocyclic ether, and mixtures thereof. 36.The solutions of claim 27, wherein the inert fluorocarbon mediumcomprises 75% perfluorooctane and 25% perfluorocyclic ether.
 37. Thesolutions of claim 27, wherein the inert fluorocarbon medium has aboiling point ranging from approximately 60° C. to approximately 100° C.38. The solutions of claim 27, further comprising a water-reactiveadditive in the nonaqueous slurry.
 39. The solutions of claim 38,wherein the water-reactive additive comprises aluminum, magnesium, orboron.
 40. The solutions of claim 27, further comprising at least oneplasticizer in the lacquer system.
 41. The solutions of claim 40,wherein the at least one plasticizer is selected from the groupconsisting of bis-dinitropropyl acetal and bis-dinitropropyl formal(“BDNPA/F”), isodecyl pelargonate (“IDP”), dioctyl adipate (“DOA”),dioctyl sebecate (“DOS”), a glycidyl azide polymer (“GAP”), and mixturesthereof.